The present invention relates to a method of controlling the supply of a toner in an electrophotographic copier.
In the art of electrophotographic copiers, there has been proposed a toner supply control method which employs a reference pattern having a predetermined reflectivity. Light image of the reference pattern is focused to the surface of a photoconductive element which is deposited with a uniform electrostatic charge, thereby forming a latent image electrostatically on the photoconductor. The latent image is developed into a toner image by a developing unit. A sensor senses a degree of toner deposition in the toner image and allows the toner supply to the developing unit to be controlled in response to an output thereof.
A problem encountered with such a prior art method is that despite the toner supply control performed as stated above, the toner cannot be adequately supplied to the developing unit when the potential on the surface of the photoconductor is unstable. The toner supply would contaminate the backgrounds of copy sheets if excessive, and allow a carrier to adhere to an image surface if short.